Refrigeration system

ABSTRACT

A refrigeration system uses a refrigerant which contains, as a main component, hydrocarbon or HFC-152a. A fluid tube, such as, a gas charge port tube is hermetically connected to a refrigerant flow passage in the refrigeration system for filling at least the refrigerant into the refrigerant flow passage. The fluid tube is sealed against leakage of the refrigerant from the refrigerant flow passage by means of a pinched portion and a squashed portion of a flat-plate shape which extends from the pinched portion to a distal end thereof. The squashed portion may be folded at a plurality of portions for enhancing the sealing effect. Further, instead of the squashed portion, an adhesive may be used for reinforcing the sealing effect provided by the pinched portion. Alternatively or with the use of the adhesive, an elastomer may be used for reinforcing the sealing effect provided by the pinched portion.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a refrigeration system for use in, suchas, an electric refrigerator.

2. Description of the Prior Art

At the meeting for revising the Montreal Protocol about the ozone layerdestructing material in the Ozone Layer Protection Treaty, it was agreedupon to wholly abolish chlorofluorocarbon (CFC) in 1996. It was alsoagreed upon to realize a large CFC reduction from 1994 to no more than25% as compared with 1986. In response to this, researches have beenactively performed by the associated makers, such as, the refrigerantmakers, the refrigeration system makers and the oil makers. As a resultof the researches, a refrigerant including, as a main component,chlorine-free fluorocarbon, particularly, known as HFC-134a, has beenwidely admitted as an alternative refrigerant for a CFC refrigerantincluding chlorine-containing fluorocarbon, particularly, CFC-12 whichhas been widely used. Further, in view of required solubility with theHFC-134a refrigerant, a lubricating oil containing an ester oil as abase oil has been developed.

FIG. 8 is a diagram schematically showing a typical conventionalrefrigeration system 15 as disclosed in, such as, Japanese First(unexamined) Patent Publication No. 4-183788. In FIG. 8, therefrigeration system 15 includes a compressor 10, a condenser 11, adrier 14, an expansion mechanism 12 in the form of a capillary tube andan evaporator 13, which are hermetically connected by piping as shown.Further, in the refrigeration system 15, the foregoing HFC-134arefrigerant and the foregoing ester lubricating oil are hermeticallyenclosed for circulation in a direction of an arrow as indicated in FIG.8.

In FIG. 8, numeral 16 denotes a typical conventional gas charge porttube, which will be described later with reference to FIG. 9 and ascompared with a preferred embodiment of the present invention.

As is known in the art, it is very difficult to find a lubricating oilwhich satisfies required solubility with HFC-134a and other propertiesrequired for a lubricating oil for use in the refrigeration system. On apractical basis, a lubricating oil satisfying such requirements islimited to the ester lubricating oil. Further, HFC-134a costs 5 to 6times as high as CFC-12. Moreover, although HFC-134a improves an ozonedestruction parameter (ODP), it is said to have some problem inimproving a global warming parameter (GWP).

In addition, since the ester oil is inferior in hydrolysis stability andhygroscopic property as compared with a mineral oil or an alkylbenzeneoil which has been widely used with, such as, CFC-12, some specialequipment is required for dehydration when the ester oil is used.Further, the ester oil costs 3 to 4 times as high as the mineral oil orthe alkylbenzene oil. Moreover, the ester oil tends to dissolve organicsubstances inside the refrigeration system so as to produce contaminantswhich are likely to block the capillary tube to lower the cooling effectof the refrigeration system. Accordingly, in order to prevent this,component parts of the refrigeration system should be washed in aparticular manner, which thus requires additional processes and costs.

SUMMARY OF THE INVENTION

Therefore, it is an object of the present invention to provide animproved refrigeration system.

According to one aspect of the present invention, a refrigeration systemcomprises a series of a refrigerant flow passage including therein acompressor, a condenser, an expansion mechanism and an evaporator; arefrigerant containing, as a main component, one of hydrocarbon andHFC-152a; a lubricating oil having solubility with the refrigerant; anda fluid tube having a base end hermetically connected to the refrigerantflow passage, a distal end and an intermediate portion extending fromthe base end to the distal end, the intermediate portion having a firstportion which is pinched to be closed and a second portion extendingfrom the first portion to the distal end, the second portion beingsquashed into a flat-plate shape to be closed.

According to another aspect of the present invention, a refrigerationsystem comprises a series of a refrigerant flow passage includingtherein a compressor, a condenser, an expansion mechanism and anevaporator; a refrigerant containing, as a main component, one ofhydrocarbon and HFC-152a; a lubricating oil having solubility with therefrigerant; and a fluid tube having a base end hermetically connectedto the refrigerant flow passage, a distal end and an intermediateportion extending from the base end to the distal end, the intermediateportion having a first portion which is pinched to be closed and asecond portion extending from the first portion to the distal end, thesecond portion receiving therein an adhesive being set so as toreinforce a sealing effect provided by the pinched first portion.

According to another aspect of the present invention, a refrigerationsystem comprises a series of a refrigerant flow passage includingtherein a compressor, a condenser, an expansion mechanism and anevaporator; a refrigerant containing, as a main component, one ofhydrocarbon and HFC-152a; a lubricating oil having solubility with therefrigerant; and a fluid tube having a base end hermetically connectedto the refrigerant flow passage, a distal end and an intermediateportion extending from the base end to the distal end, the intermediateportion having a first portion which is pinched to be closed and asecond portion extending from the first portion to the distal end, thesecond portion receiving therein an elastomer having a diametersubstantially equal to an inner diameter of the second portion, thesecond portion having a third portion which is deformed to reduce asectional area thereof so that an inner wall of the third portiontightly fits on the elastomer.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be understood more fully from the detaileddescription given hereinbelow and from the accompanying drawings of thepreferred embodiments of the invention, which are given by way ofexample only, and are not intended to limit the present invention.

In the drawings:

FIG. 1 is a perspective view showing a refrigeration system of anelectric refrigerator according to a first preferred embodiment of thepresent invention;

FIG. 2 is a sectional view taken along line A--A in FIG. 1;

FIG. 3 is a perspective view showing a gas charge port tube shown inFIG. 2, in the state where the gas charge port tube is sealed accordingto the first preferred embodiment;

FIG. 4 is a perspective view showing a gas charge port tube shown inFIG. 2, in the state where the gas charge port tube is sealed accordingto a second preferred embodiment of the present invention;

FIG. 5 is a partly-sectioned perspective view showing a gas charge porttube shown in FIG. 2, in the state where the gas charge port tube issealed according to a third preferred embodiment of the presentinvention;

FIG. 6 is a partly-sectioned perspective view showing a gas charge porttube shown in FIG. 2, in the state where the gas charge port tube issealed according to a fourth preferred embodiment of the presentinvention;

FIG. 7 is a sectional view taken along line B--B in FIG. 6;

FIG. 8 is a diagram schematically showing a conventional refrigerationsystem; and

FIG. 9 is a perspective view showing a gas charge port tube in the statewhere the gas charge port tube is sealed according to the prior art.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Now, preferred embodiments of the present invention will be describedhereinbelow with reference to the accompanying drawings.

FIG. 1 shows a refrigeration system 20 of an electric refrigeratoraccording to a first preferred embodiment of the present invention. Therefrigeration system 20 includes a compressor 21, a condenser 22, anexpansion mechanism 23, an evaporator 24 and a drier 25, which arehermetically connected by piping 26 so as to form a series of arefrigerant flow passage.

FIG. 2 is a sectional view taken along line A--A in FIG. 1. In FIG. 2,the compressor 21 has a sealed casing 27 which includes therein acompression element 28 and a motor element 29 for driving thecompression element 28. Numeral 30 denotes a joint tube which is brazedto the sealed casing 27. A gas charge port tube 31 has a base endhermetically coupled to the joint tube 30 and a tip or distal endhermetically closed by an in-process sealing plug 32. The in-processsealing plug 32 is integrally formed with an evacuation port 33 which isclosed by a cap in FIG. 2. An evacuation tube 34 has a base endhermetically coupled to one of ports 25a, 25a of the drier 25 and a tipor distal end hermetically closed by the in-process sealing plug 32 withthe evacuation port 33 in the same manner as the distal end of the gascharge port tube 31.

In this preferred embodiment, hydrocarbon, such as, propane or butane,or chlorine-free fluorocarbon known as HFC-152a is used as a maincomponent of a refrigerant for the refrigeration system 20. Accordingly,both ODP and GWP can be highly improved. Further, the mineral oil or thealkylbenzene oil can be used due to high solubility with hydrocarbon andHFC-152a. Accordingly, the problem of the capillary tube being blockedby the ester produced contaminants can be eliminated to make itunnecessary to wash the component parts of the refrigeration system.Further, the special equipment for dehydration required for the esteroil becomes unnecessary, either. Still further, hydrocarbon costs lessas compared with HFC-134a. As a result, according to this preferredembodiment, the refrigeration system can be provided at a reduced costas compared with the refrigeration system using the HFC-134a refrigerantand the ester lubricating oil.

On the other hand, as appreciated, hydrocarbon and HFC-152a both arecombustible. Accordingly, the refrigerant including one of these as amain component can not be dealt with like the refrigerant includingHFC-134a as a main component.

Hereinbelow, evacuation of the refrigeration system 20 and filling ofthe lubricating oil and the refrigerant into the refrigeration system 20will be described according to this preferred embodiment.

Before the foregoing evacuation and filling, fluid tubes other than thegas charge port tube 31 and the evacuation tube 34 are closed by brazingusing naked or open flanges, in such a manner as to form theaforementioned series of the refrigerant flow passage through therefrigeration system 20. Subsequently, the in-process sealing plugs 32,32 are mounted onto the fluid tubes 31 and 34, respectively, as shown inFIG. 2. Thereafter, the evacuation is performed via the evacuation ports33 until the inside of the refrigeration system 20 reaches a givenvacuum value or degree. After the evacuation is finished, the evacuationtube 34 is pinched by a pinching jig (not shown) so as to be closed.Subsequently, the in-process sealing plug 32 is removed from theevacuation tube 34, and the distal end of the evacuation tube 34 isbrazed to be closed using the open flames. It may be arranged to firstpinch the distal end of the evacuation tube 34 and then braze thepinched distal end using the open flames.

Thereafter, a coupler (not shown) is mounted onto the evacuation port 33of the in-process sealing plug 32 attached to the gas charge port tube31 for filling a given amount of the mineral or alkylbenzene lubricatingoil into the refrigerant flow passage of the refrigeration system 20 viathe evacuation port 33. Subsequently, the refrigerant containing, as amain component, hydrocarbon, such as, propane or butane, or HFC-152a, isfilled into the refrigerant flow passage via the evacuation port 33.

Finally, the gas charge port tube 31 is closed or sealed in thefollowing manner:

In FIG. 3, a pinch portion 31a of the gas charge port tube 31 is firstpinched to be closed using the pinching jig, and then the in-processsealing plug 32 is removed from the gas charge port tube 31.Subsequently, a portion 31b of the gas charge port tube 31 extendingfrom the pinch portion 31a to the distal end 31c is squashed or crushedinto a flat-plate shape to be closed using the pinching jig or a rollerjig (not shown). In this preferred embodiment, the gas charge port tube31 is formed by an annealed deoxidized copper tube so that the squash ofthe portion 31b can be easily performed.

A length of the portion 31b to be squashed is set to be relatively long.Specifically, the length thereof is determined to a value which ensuresno leakage of the combustible refrigerant gas via the gas charge porttube 31 when the portion 31b is squashed by the jig. As a result, thedistal end 31c of the gas charge port tube 31 can be sealed not only bysoldering using a soldering iron but also by brazing using the openflames or by gas or seam welding, without danger of explosion or fire.

For comparison, a conventional sealing manner of the gas charge porttube 16 will be described hereinbelow with reference to FIG. 9.

In FIG. 9, a pinch portion 17 of the gas charge port tube 16 is firstpinched after the evacuation, which is the same as in this preferredembodiment. Subsequently, a distal end 19 is pinched and then brazed tobe sealed while a portion 18 from the pinch portion 17 to the distal end19 remains as it is. According to this conventional sealing manner, therefrigerant gas remains inside the portion 18, and further, the scalingof the gas charge port tube 16 provided by the pinched portions 17 and19 is somewhat poor. As a result, when the refrigerant gas iscombustible as in this preferred embodiment, the explosion or firebecomes a serious problem, particularly, during brazing or welding thedistal end 19 using the open flames.

As appreciated from the foregoing description, according to thispreferred embodiment, the combustible refrigerant containing, as a maincomponent, hydrocarbon or HFC-152a can be used in the refrigerationsystem without danger of the explosion or fire. Further, the use of sucha refrigerant makes it possible to use the mineral or alkylbenzenelubricating oil.

It may be arranged that the evacuation tube 34 is also sealed like thegas charge port tube 31.

Now, a second preferred embodiment of the present invention will bedescribed hereinbelow with reference to FIG. 4. In FIG. 4, elementscorresponding to those in the first preferred embodiment are representedby the same reference marks or symbols.

As shown in FIG. 4, in the second preferred embodiment, the squashedportion 31b of the gas charge port tube 31 is bent or folded at aplurality of portions 35, 36, 37 and 38. As a result, the sealing effectfor the gas charge port tube 31 can be further enhanced.

The other structure is the same as in the foregoing first preferredembodiment.

In the first and second preferred embodiments, it may be arranged thatan adhesive, such as, an epoxy resin adhesive is filled in the portion31b of the gas charge port tube 31 before it is squashed. Thisarrangement further enhances the sealing effect of the gas charge porttube 31 against leakage of the refrigerant gas.

Now, a third preferred embodiment of the present invention will bedescribed hereinbelow with reference to FIG. 5. In FIG. 5, elementscorresponding to those in the first preferred embodiment are representedby the same reference marks or symbols.

In the third preferred embodiment, after the pinch portion 31a of thegas charge port tube 31 is pinched and the in-process sealing plug 32 isremoved as in the first preferred embodiment, an adhesive, such as, atwo-part epoxy resin adhesive is filled in a cap 40 which is thenmounted onto an end portion 41 extending from the pinch portion 31a tothe distal end 31c. As a result, the adhesive is set at portions asindicated by numeral 42 to reinforce the sealing effect provided by thepinch portion 31a so that the gas charge port tube 31 is reliably sealedagainst leakage of the refrigerant gas.

The other structure is the same as in the foregoing first preferredembodiment.

Now, a fourth preferred embodiment of the present invention will bedescribed hereinbelow with reference to FIGS. 6 and 7. In FIG. 6,elements corresponding to those in the first preferred embodiment arerepresented by the same reference marks or symbols.

In the fourth preferred embodiment, after the pinch portion 31a of thegas charge port tube 31 is pinched and the in-process sealing plug 32 isremoved as in the first preferred embodiment, an elastomer 50 isinserted into an end portion 51 extending from the pinch portion 31a tothe distal end 31c. A diameter of the elastomer 50 is substantiallyequal to an inner diameter of the end portion 51. The elastomer 50 ismade of nitrile rubber which is excellent in oil- and heat-proof orurethane rubber which is excellent in mechanical strength.

After the insertion of the elastomer 50, the end portion 51 is deformedat a portion 52 so as to reduce a sectional area of the portion 52.Accordingly, an inner wall of the portion 52 tightly fits on a peripheryof the elastomer 50 all over its circumference so as to ensure thereliable sealing of the gas charge port tube 31 against leakage of therefrigerant gas, as clearly seen from FIG. 7 which is a sectional viewtaken along line B--B in FIG. 6. Thereafter, a distal end portion 53 ofthe gas charge port tube 31 is pinched as shown in FIG. 6. Since theleakage of the refrigerant gas is reliably prevented at the deformedportion 52, the distal end portion 53 can be sealed at a portion 54 bymeans of the soldering using the soldering iron, the brazing using theopen flames or the gas or seam welding, without danger of explosion orfire.

In the fourth preferred embodiment, an adhesive 55, such as, an epoxyresin adhesive may be filled in between the pinch portion 31a and theelastomer 50 so as to further enhance the sealing effect.

The other structure is the same as in the foregoing first preferredembodiment.

It is to be understood that this invention is not to be limited to thepreferred embodiments and modifications described above, and thatvarious changes and modifications may be made without departing from thespirit and scope of the invention as defined in the appended claims.

What is claimed is:
 1. A refrigeration system comprising:a series of arefrigerant flow passage including therein a compressor, a condenser, anexpansion mechanism and an evaporator; a refrigerant containing, as amain component, one of hydrocarbon and HFC-152a; and a lubricating oilhaving solubility with said refrigerant; said refrigerant and saidlubricating oil contained in said refrigerant flow passage; saidrefrigeration system further comprising: a fluid tube having a base endhermetically connected to said refrigerant flow passage, a distal endand an intermediate portion extending from said base end to said distalend, said intermediate portion having a first portion which is pinchedto be closed and a second portion extending from said first portion tosaid distal end, said second portion being squashed into a flat-plateshape so as to be closed.
 2. The refrigeration system as set forth inclaim 1, wherein said distal end is sealed by soldering.
 3. Therefrigeration system as set forth in claim 1, wherein said distal end issealed by welding.
 4. The refrigeration system as set forth in claim 1,wherein said fluid tube is a gas charge port tube for introducing atleast said refrigerant into said refrigerant flow passage before it ispinched and squashed.
 5. The refrigeration system as set forth in claim1, wherein said squashed second portion is folded at a plurality ofportions.
 6. The refrigeration system as set forth in claim 1, whereinan adhesive is disposed in said squashed second portion.
 7. Therefrigeration system as set forth in claim 6, wherein said squashedsecond portion is folded at a plurality of portions.